The present invention relates to air filter assemblies of the multiple Vee-panel type and, more particularly, to an improvement in the mounting of the filter panels therein. In such filter assemblies a plurality of pairs of relatively flat filter panels are angularly mounted in a support frame so as to define a corresponding plurality of adjacent Vees. The apexes of the formed Vees are disposed adjacent the air outlet end of the filter assembly and the open ends of the Vees define air inlets. Typically, a plurality of such filter assemblies are replaceably mounted in adjacent juxtaposition in a large master holding frame secured to a large air duct. In recent years the multi-Vee panel type air filter has become widely used in numerous different applications due to the ability of the Vee-panel configuration to accommodate efficiently large volumes of different types of filter media with a minimum pressure drop across the filter assembly.
Until recently the individual filter panels in a multi-Vee panel filter assembly were generally permanently mounted in the support frame due to the difficulty of obtaining an airtight seal between replaceable panels and the support frame at the rear end of the assembly. As a result, when the individual filter panels needed replacement, it was necessary to remove and replace the entire filter assembly. This was not only costly but created both handling and disposal problems due to the bulk of the support frame and the fact that installations generally employed several such filter assemblies bolted together in the master holding frame. With the diminishing availability of landfill disposal sites, the problem of filter disposal was becoming increasingly acute.
A solution to these problems is found in applicant's U.S. Pat. No. 5,223,011. The multiple Vee-panel air filter assemblies disclosed therein employ a novel camming mechanism for each complementary pair of angularly disposed panels which maintains the necessary seals between the individual filter panels and the assembly frame at the rear ends thereof and enables the panels to be slidably mounted and readily replaceable within the frame. Compressible sealing gaskets are disposed about open side portions of the frame to provide airtight perimeter compression seals between the frame and the outer sides of the filter panels. At least one of the panels in each of the complementary pairs of panels define an elongated cam surface extending vertically along a rear side portion thereof adjacent the inner rear edge of the panel. The cam surface is inclined rearwardly and inwardly within the frame upon the cam carrying panel being slid into position within the frame. As the complementary panel is slid into the frame so as to form a Vee with the first panel, the inner rear edge of the complementary panel abuts and slides over the cam surface on the first panel, forcing the two panels apart at the rear ends thereof such that they compress the adjacent portions of the sealing gaskets carried by the frame.
To complete and maintain the desired airtight compression seals between the support frame and the entire outer perimeters of the outer sides of the filter panels, a pair of locking clips are provided on each panel at or adjacent the forward ends thereof. The locking clips are adapted to releasibly engage portions of the support frame upon the forward end portion of a filter panel being pressed outwardly against the frame, whereupon the sealing gasket is continuously compressed against the frame about the panel. Thus, to replace the filter panels in the filter assembly disclosed in U.S. Pat. No. 5,223,011, it is only necessary to disengage the locking clips from the frames, withdraw the old panels, slide in the new panels and repeat the aforesaid camming and locking steps.
While the above-described filter assembly represented a substantial improvement in multiple Vee type filter assemblies, it had certain shortcomings. To mount the filter assembly on a master mounting frame it was still necessary to bolt the individual filter assemblies together and to the master holding frame. This was generally accomplished by providing each individual filter assembly with a square or rectangular mounting frame, depending on the shape of the filter assembly, which would be welded onto the filter assembly frame about the forward or air inlet end thereof and project forwardly therefrom. The mounting frame thus provides an attachment surface for the securement of the filter assembly to the mounting frame of an adjacent filter assembly and to the master holding frame. It also provided a support frame for the mounting of a pre-filter at the inlet end of the filter assembly. Thus, while these filter assemblies were removably secured to the master holding frame by means of the mounting frames, removal and securement both required a time intensive operation, quite unlike the removal and securement of the individual filter panels within the filter assembly.
While the camming and locking mechanisms in the above-described patented filter assembly do provide releasable perimeter seals about individually removable filter panels, they limit the flexibility of the filter assembly. To maintain airtight perimeter seals about the filter panels, the sealing gasket about each panel should be compressed by about 50% between the panel and the assembly frame. This was achieved in the filter assemblies disclosed in U.S. Pat. No. 5,223,011 by sizing the rear portion of the assembly frame relative to the widths of the filters panels to be held therein. The panel retention flanges on the assembly frame which carry the sealing gaskets adjacent the outer rearward ends of each pair of complementary filter panels were spaced apart a distance equal to the combined thicknesses of the complementary filter panels plus the offset of the cam surface or surfaces thereon and the thickness of an uncompressed sealing gaskets. As a result, a given filter frame could only be used with filter panels of a given transverse dimension. While this dimension could be varied somewhat by varying the offset of the elongated cam surfaces and/or the thickness of the sealing gaskets, the extent of the variance is quite limited by the configuration of the camming mechanism. This is significant because the transverse dimension of the filter panels in the patented assembly determined the depth of the filter media contained therein and the depth of the filter media through which the air flow passes directly affects pertinent air filter characteristics, e.g., dust holding capacity, efficiency and pressure loss. etc.. Thus, if a particular application required more than a very minor change in the depth of filter media to provide the desired air filter characteristics, a differently sized frame was required.
Different filter applications and economic considerations frequently dictate changes in the filter media used in these filter assemblies. Different filter medias frequently have different depth requirements to obtain the desired air filter characteristics. Accordingly, the above-described filter assemblies are also relatively limited with regard to the use of different medias. While they can indeed be used with a wide variety of filtering medias, variations in filter media will often require different panel thicknesses and thus the use of differently sized frames.
The filter assembly of the present invention retains all of the advantages of the assemblies disclosed in U.S. Pat. No. 5,233,011 and obviates the mounting and versatility of problems noted above. With the present invention, the same filter frame can be used with filter panels employing a wide variety of different medias and wherein the depth of the media can vary significantly. The individual filter panels are interchangeable throughout the entire filter assembly to facilitate panel replacement and avoid the need to use different panel configurations in each complementary pair of panels. The filter assembly of the present invention is also capable of being removably attached to a master holding frame without the need for any tools and can be easily detached therefrom. The present invention further provides an improved locking mechanism for holding the filter panels in sealing engagements with the frame and additionally utilizes a filter panel which is of a more economical construction than the removable panels heretofore in use.